How did Dmitri Mendeleev group the elements in his original periodic table?

• A. By alphabetical order of element names
• B. By increasing atomic mass and similar chemical properties
• C. By increasing atomic number only
• D. By their physical state at room temperature

Answer: (B)

Verified step by step guidance

1. Understand that Dmitri Mendeleev's original periodic table was an early attempt to organize elements based on their properties before the modern atomic number concept was established.
2. Recognize that Mendeleev arranged elements primarily by increasing atomic mass, which was the best available measure at the time to order elements systematically.
3. Note that Mendeleev also grouped elements with similar chemical properties into the same columns (groups), allowing patterns and periodic trends to emerge.
4. Realize that this method allowed Mendeleev to predict the existence and properties of undiscovered elements by leaving gaps in his table where the pattern suggested missing elements.
5. Conclude that Mendeleev's grouping was not alphabetical, nor based solely on atomic number or physical state, but rather by increasing atomic mass combined with grouping elements of similar chemical behavior.